diesel::expression

Struct CaseWhen

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pub struct CaseWhen<Whens, E> { /* private fields */ }
Expand description

A SQL CASE WHEN ... END expression

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impl<Whens, E> CaseWhen<Whens, E>

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pub fn when<C, T>(self, condition: C, if_true: T) -> When<Self, C, T>
where Self: CaseWhenTypesExtractor<Whens = Whens, Else = E>, C: Expression, <C as Expression>::SqlType: BoolOrNullableBool, T: AsExpression<<Self as CaseWhenTypesExtractor>::OutputExpressionSpecifiedSqlType>,

Add an additional WHEN ... THEN ... branch to the CASE expression

See the case_when documentation for more details.

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impl<Whens> CaseWhen<Whens, NoElseExpression>

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pub fn otherwise<E>(self, if_no_other_branch_matched: E) -> Otherwise<Self, E>
where Self: CaseWhenTypesExtractor<Whens = Whens, Else = NoElseExpression>, E: AsExpression<<Self as CaseWhenTypesExtractor>::OutputExpressionSpecifiedSqlType>,

Sets the ELSE branch of the CASE expression

It is named this way because else is a reserved keyword in Rust

See the case_when documentation for more details.

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impl<Whens, E, __Rhs> Add<__Rhs> for CaseWhen<Whens, E>
where Self: Expression, <Self as Expression>::SqlType: Add, <<Self as Expression>::SqlType as Add>::Rhs: SqlType + SingleValue, __Rhs: AsExpression<<<Self as Expression>::SqlType as Add>::Rhs>,

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type Output = Add<CaseWhen<Whens, E>, <__Rhs as AsExpression<<<CaseWhen<Whens, E> as Expression>::SqlType as Add>::Rhs>>::Expression>

The resulting type after applying the + operator.
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fn add(self, rhs: __Rhs) -> Self::Output

Performs the + operation. Read more
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impl<Whens: Clone, E: Clone> Clone for CaseWhen<Whens, E>

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fn clone(&self) -> CaseWhen<Whens, E>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<Whens: Debug, E: Debug> Debug for CaseWhen<Whens, E>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<Whens, E, __Rhs> Div<__Rhs> for CaseWhen<Whens, E>
where Self: Expression, <Self as Expression>::SqlType: Div, <<Self as Expression>::SqlType as Div>::Rhs: SqlType + SingleValue, __Rhs: AsExpression<<<Self as Expression>::SqlType as Div>::Rhs>,

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type Output = Div<CaseWhen<Whens, E>, <__Rhs as AsExpression<<<CaseWhen<Whens, E> as Expression>::SqlType as Div>::Rhs>>::Expression>

The resulting type after applying the / operator.
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fn div(self, rhs: __Rhs) -> Self::Output

Performs the / operation. Read more
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impl<W, T, Whens, E> Expression for CaseWhen<CaseWhenConditionsIntermediateNode<W, T, Whens>, E>
where CaseWhen<CaseWhenConditionsLeaf<W, T>, E>: Expression, CaseWhen<Whens, E>: Expression<SqlType = <CaseWhen<CaseWhenConditionsLeaf<W, T>, E> as Expression>::SqlType>,

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type SqlType = <CaseWhen<CaseWhenConditionsLeaf<W, T>, E> as Expression>::SqlType

The type that this expression represents in SQL
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impl<W, T, E> Expression for CaseWhen<CaseWhenConditionsLeaf<W, T>, ElseExpression<E>>
where W: Expression, <W as Expression>::SqlType: BoolOrNullableBool, T: Expression,

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type SqlType = <T as Expression>::SqlType

The type that this expression represents in SQL
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impl<W, T> Expression for CaseWhen<CaseWhenConditionsLeaf<W, T>, NoElseExpression>
where W: Expression, <W as Expression>::SqlType: BoolOrNullableBool, T: Expression, <T as Expression>::SqlType: IntoNullable, <<T as Expression>::SqlType as IntoNullable>::Nullable: SqlType + TypedExpressionType,

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type SqlType = <<T as Expression>::SqlType as IntoNullable>::Nullable

The type that this expression represents in SQL
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impl<Whens, E, __Rhs> Mul<__Rhs> for CaseWhen<Whens, E>
where Self: Expression, <Self as Expression>::SqlType: Mul, <<Self as Expression>::SqlType as Mul>::Rhs: SqlType + SingleValue, __Rhs: AsExpression<<<Self as Expression>::SqlType as Mul>::Rhs>,

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type Output = Mul<CaseWhen<Whens, E>, <__Rhs as AsExpression<<<CaseWhen<Whens, E> as Expression>::SqlType as Mul>::Rhs>>::Expression>

The resulting type after applying the * operator.
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fn mul(self, rhs: __Rhs) -> Self::Output

Performs the * operation. Read more
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impl<Whens, E, DB> QueryFragment<DB> for CaseWhen<Whens, E>
where DB: Backend, Whens: QueryFragment<DB>, E: QueryFragment<DB>,

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fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, DB>) -> QueryResult<()>

Walk over this QueryFragment for all passes. Read more
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fn to_sql(&self, out: &mut DB::QueryBuilder, backend: &DB) -> QueryResult<()>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.
Converts this QueryFragment to its SQL representation. Read more
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fn collect_binds<'b>( &'b self, out: &mut DB::BindCollector<'b>, metadata_lookup: &mut DB::MetadataLookup, backend: &'b DB, ) -> QueryResult<()>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.
Serializes all bind parameters in this query. Read more
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fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.
Is this query safe to store in the prepared statement cache? Read more
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fn is_noop(&self, backend: &DB) -> QueryResult<bool>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.
Does walking this AST have any effect?
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impl<Whens: QueryId, E: QueryId> QueryId for CaseWhen<Whens, E>

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const HAS_STATIC_QUERY_ID: bool = _

Can the SQL generated by Self be uniquely identified by its type? Read more
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type QueryId = CaseWhen<<Whens as QueryId>::QueryId, <E as QueryId>::QueryId>

A type which uniquely represents Self in a SQL query. Read more
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fn query_id() -> Option<TypeId>

Returns the type id of Self::QueryId if Self::HAS_STATIC_QUERY_ID. Returns None otherwise. Read more
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impl<Whens, E, __Rhs> Sub<__Rhs> for CaseWhen<Whens, E>
where Self: Expression, <Self as Expression>::SqlType: Sub, <<Self as Expression>::SqlType as Sub>::Rhs: SqlType + SingleValue, __Rhs: AsExpression<<<Self as Expression>::SqlType as Sub>::Rhs>,

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type Output = Sub<CaseWhen<Whens, E>, <__Rhs as AsExpression<<<CaseWhen<Whens, E> as Expression>::SqlType as Sub>::Rhs>>::Expression>

The resulting type after applying the - operator.
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fn sub(self, rhs: __Rhs) -> Self::Output

Performs the - operation. Read more
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impl<Whens, E, __GroupByClause> ValidGrouping<__GroupByClause> for CaseWhen<Whens, E>
where Whens: ValidGrouping<__GroupByClause>, E: ValidGrouping<__GroupByClause>, Whens::IsAggregate: MixedAggregates<E::IsAggregate>,

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type IsAggregate = <<Whens as ValidGrouping<__GroupByClause>>::IsAggregate as MixedAggregates<<E as ValidGrouping<__GroupByClause>>::IsAggregate>>::Output

Is this expression aggregate? Read more
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impl<W, T, Whens, E, QS> AppearsOnTable<QS> for CaseWhen<CaseWhenConditionsIntermediateNode<W, T, Whens>, E>
where Self: Expression, W: AppearsOnTable<QS>, T: AppearsOnTable<QS>, CaseWhen<Whens, E>: AppearsOnTable<QS>,

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impl<W, T, E, QS> AppearsOnTable<QS> for CaseWhen<CaseWhenConditionsLeaf<W, T>, ElseExpression<E>>
where CaseWhen<CaseWhenConditionsLeaf<W, T>, ElseExpression<E>>: Expression, W: AppearsOnTable<QS>, T: AppearsOnTable<QS>, E: AppearsOnTable<QS>,

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impl<W, T, QS> AppearsOnTable<QS> for CaseWhen<CaseWhenConditionsLeaf<W, T>, NoElseExpression>
where CaseWhen<CaseWhenConditionsLeaf<W, T>, NoElseExpression>: Expression, W: AppearsOnTable<QS>, T: AppearsOnTable<QS>,

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impl<Whens: Copy, E: Copy> Copy for CaseWhen<Whens, E>

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impl<W, T, Whens, E, QS> SelectableExpression<QS> for CaseWhen<CaseWhenConditionsIntermediateNode<W, T, Whens>, E>
where Self: AppearsOnTable<QS>, W: SelectableExpression<QS>, T: SelectableExpression<QS>, CaseWhen<Whens, E>: SelectableExpression<QS>,

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impl<W, T, E, QS> SelectableExpression<QS> for CaseWhen<CaseWhenConditionsLeaf<W, T>, ElseExpression<E>>
where CaseWhen<CaseWhenConditionsLeaf<W, T>, ElseExpression<E>>: AppearsOnTable<QS>, W: SelectableExpression<QS>, T: SelectableExpression<QS>, E: SelectableExpression<QS>,

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impl<W, T, QS> SelectableExpression<QS> for CaseWhen<CaseWhenConditionsLeaf<W, T>, NoElseExpression>
where CaseWhen<CaseWhenConditionsLeaf<W, T>, NoElseExpression>: AppearsOnTable<QS>, W: SelectableExpression<QS>, T: SelectableExpression<QS>,

Auto Trait Implementations§

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impl<Whens, E> Freeze for CaseWhen<Whens, E>
where Whens: Freeze, E: Freeze,

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impl<Whens, E> RefUnwindSafe for CaseWhen<Whens, E>
where Whens: RefUnwindSafe, E: RefUnwindSafe,

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impl<Whens, E> Send for CaseWhen<Whens, E>
where Whens: Send, E: Send,

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impl<Whens, E> Sync for CaseWhen<Whens, E>
where Whens: Sync, E: Sync,

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impl<Whens, E> Unpin for CaseWhen<Whens, E>
where Whens: Unpin, E: Unpin,

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impl<Whens, E> UnwindSafe for CaseWhen<Whens, E>
where Whens: UnwindSafe, E: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T, ST> AsExpression<ST> for T
where T: Expression<SqlType = ST>, ST: SqlType + TypedExpressionType,

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type Expression = T

The expression being returned
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fn as_expression(self) -> T

Perform the conversion
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<Conn, DB, T> ExecuteDsl<Conn, DB> for T
where Conn: Connection<Backend = DB>, DB: Backend, T: QueryFragment<DB> + QueryId,

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fn execute(query: T, conn: &mut Conn) -> Result<usize, Error>

Execute this command
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoSql for T

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fn into_sql<T>(self) -> AsExprOf<Self, T>
where Self: AsExpression<T> + Sized, T: SqlType + TypedExpressionType,

Convert self to an expression for Diesel’s query builder. Read more
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fn as_sql<'a, T>(&'a self) -> AsExprOf<&'a Self, T>
where &'a Self: AsExpression<T>, T: SqlType + TypedExpressionType,

Convert &self to an expression for Diesel’s query builder. Read more
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impl<T> NullableExpressionMethods for T
where T: Expression,

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fn nullable(self) -> Nullable<Self>

Converts this potentially non-null expression into one which is treated as nullable. This method has no impact on the generated SQL, and is only used to allow certain comparisons that would otherwise fail to compile. Read more
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fn assume_not_null(self) -> AssumeNotNull<Self>

Converts this potentially nullable expression into one which will be assumed to be not-null. This method has no impact on the generated SQL, however it will enable you to attempt deserialization of the returned value in a non-Option. Read more
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impl<T> PgExpressionMethods for T
where T: Expression,

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fn is_not_distinct_from<T>(self, other: T) -> IsNotDistinctFrom<Self, T>
where Self::SqlType: SqlType, T: AsExpression<Self::SqlType>,

Available on crate feature postgres_backend only.
Creates a PostgreSQL IS NOT DISTINCT FROM expression. Read more
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fn is_distinct_from<T>(self, other: T) -> IsDistinctFrom<Self, T>
where Self::SqlType: SqlType, T: AsExpression<Self::SqlType>,

Available on crate feature postgres_backend only.
Creates a PostgreSQL IS DISTINCT FROM expression. Read more
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impl<T, DB> QueryFragmentForCachedStatement<DB> for T
where DB: Backend, <DB as Backend>::QueryBuilder: Default, T: QueryFragment<DB>,

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fn construct_sql(&self, backend: &DB) -> Result<String, Error>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.
Convert the query fragment into a SQL string for the given backend
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fn is_safe_to_cache_prepared(&self, backend: &DB) -> Result<bool, Error>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.
Check whether it’s safe to cache the query
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impl<T> SqliteExpressionMethods for T
where T: Expression,

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fn is<T>(self, other: T) -> Is<Self, T>
where Self::SqlType: SqlType, T: AsExpression<Self::SqlType>,

Available on crate feature sqlite only.
Creates a Sqlite IS expression. Read more
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fn is_not<T>(self, other: T) -> IsNot<Self, T>
where Self::SqlType: SqlType, T: AsExpression<Self::SqlType>,

Available on crate feature sqlite only.
Creates a Sqlite IS NOT expression. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> ErasedDestructor for T
where T: 'static,

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impl<T> MaybeSendSync for T

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impl<T, Base> RefNum<Base> for T
where T: NumOps<Base, Base> + for<'r> NumOps<&'r Base, Base>,